Errata

Wiring for the trickle charger is not clear.

Change:
The circuit is wired as shown in Figure 4-16. The battery is connected to both the robot
and charger when it is switched on, enabling the Arduino to monitor and display the
battery voltage. The connection via the resistor to pin 13 is required to tell the Arduino
that a charger is connected so it can monitor the voltage instead of driving the robot.

Figure 4-16. Wiring for trickle charging with Arduino Voltage Monitoring

To:

The circuit is wired as shown in Figure 4-16. The battery positive lead is connected to center pole of the switch. One switch pole is connected to the +M power input connection on the motor shield, the other switch pole is connected to the resistor that is wired to the charging jack via the diode. With the switch as shown In figure 4-16, the toggle will be up to power the robot, down to trickle charge.

Figure 4-16. Wiring for trickle charging


Although not needed for the standard functionality, figure 4-17 shows an additional blue wire that can be used to connect the charging socket so Arduino can automatically detect when the charger is connected. Figure 3-19 has a clearer picture of where this wire connects to the socket and Appendix D contains code that reads this pin. However, this capability is only required if you implement the optional battery monitoring capability discussed in Appendix D.

Figure 4-25 disagrees with figure 4-26. Both indicate the motor connections to the motor shield but the polarity of two of the motors isn't clear. Which figure is correct?

Thanks,
Rob

Note from the Author or Editor:
If you have soldered the motor connections so the wires near the top plate are the same color, then the front and back motors should be reversed, as shown in figure 4-25. Otherwise use figure 4-26.

Because you should test the motor directions anyway and because it's easy to swap the connections at the shield, it actually doesn't matter how you have wired the motors as long as you test that the motors run in the correct direction using the test code. Just make sure that you swap the black and red wires at the motor shield terminals for any motors running in the wrong direction in the test.

The trickle charge discussion and diagram don't convey enough information to correctly wire the circuit.

There is discussion and a diagram about the trickle charge circuit page 32 and then discussion again on page 229, but I believe we need a schematic because I can't tell from the diagram which element of the plug the anode of the reverse voltage protection diode is connected to.

I believe it is the center conductor of the plug, because the diode will conduct only if the voltage is more positive at the anode then the cathode. The diagram, looks like it's connected to the shield of the plug.

Please advise.

Note from the Author or Editor:
The following text should be added to page 32 and page 55 preceding the sentence: See (page 229) for information about using the charger."

The charging jack has three tabs, locate the tab for the center pin (its the one attached with a rivet visible from the back of the jack), this connects to the positive end of the diode (the circular band on the diode identifies the cathode- the negative end). The tab next this is connected to ground.